fix usage of GetPixelRowSpan().

src/ImageSharp.Drawing/Brushes/Processors/BrushApplicator.cs

@@ -78,7 +78,7 @@ namespace SixLabors.ImageSharp.Drawing.Brushes.Processors
                     overlay[i] = this[x + i, y];
                 }
 
-                Span<TPixel> destinationRow = this.Target.GetPixelRowSpan(x).Slice(y, scanline.Length);
+                Span<TPixel> destinationRow = this.Target.GetPixelRowSpan(y).Slice(x, scanline.Length);
                 this.Blender.Blend(destinationRow, destinationRow, overlay, amountBuffer);
             }
         }

src/ImageSharp/Processing/Processors/Transforms/CropProcessor.cs

@@ -52,7 +52,7 @@ namespace SixLabors.ImageSharp.Processing.Processors
                     source.Configuration.ParallelOptions,
                     y =>
                     {
-                        Span<TPixel> sourceRow = source.GetPixelRowSpan(minX).Slice(y);
+                        Span<TPixel> sourceRow = source.GetPixelRowSpan(y).Slice(minX);
                         Span<TPixel> targetRow = targetPixels.GetRowSpan(y - minY);
                         SpanHelper.Copy(sourceRow, targetRow, maxX - minX);
                     });